Catheter ablation using radiofrequency is a new therapeutic tool to treat atrial fibrillation with a higher success rate than medical therapy (80% versus less than 50% respectively). Because of the length of the intervention and of the risk of complications of the procedure, it would be important to determine success rate before the intervention. The information gained from this study will in all probability improve our estimation of the chances of a successful intervention and may enable us to take necessary therapeutic measures in case of an elevated risk of recurrence.